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2nd Submission Cleve Hill Battery

23/503812/SUB | Submission of Details to Discharge condition 3 – Battery Safety, Phase 2, land at Cleve Hill Graveney ME13 9EE

Made by Professor Sir David Melville CBE BSc PhD FInstP CPhys HonDSc Sen Member IEEE(USA)

In our earlier submission of 23 Aug 2023 we outlined our serious concerns arising from preliminary information on the BSMP. Having now had the opportunity to study the BSMP in detail we confirm that all of the issues raised are still unresolved and outline additional matters below.

We note in particular that there is no evidence that SBC have taken any independent advice as advocated in our earlier submission. This calls into question the LPA’s ability to make an informed judgement on the merits of the CHSP submission.

Our conclusion is that the BSMP is inadequate, misrepresents and fails to take account of experience of battery fires elsewhere, has a dangerously cursory approach to toxic gas emissions and water requirements, lacks sufficient detail to make a judgement and fails to address important matters raised by KFRS and the Faversham Society .

We strongly urge that the proposal is rejected.

A number of  central points in our objection are summarised here

  1. The current proposal in the BSMP is for a 300MWh BESS with a possible almost five-fold expansion to 1400MWh. The latter represents a large and material difference and would constitute one of the largest in the world making this an essentially different application compared to that covered by the DCO. Despite the fact that is contrary to the provisions in the DCO, It would entail a significant re-design of the site layout. For example, the current site diagram only allows for a possible doubling of the battery size and is constrained by the proposed bund. The potential for thermal runaway incidents and explosions would also increase five-fold.
  2. Explosion hazard has been demonstrated in several actual BESS incidents and represents a physical hazard related to fire, but presents different problems. The interplay between factors tending to immediate ignition (fire) and delayed ignition (typically producing explosion) is complex. It is proposed that LFP batteries are to be deployed. It is a well-established fact that the LFP batteries proposed for Cleve Hill are more subject to explosion risk than NMC batteries. The BSMP (31) dangerously fails to acknowledge this and so to take to it into account. Explosion of its nature cannot be mitigated, only a consequent fire can be. The BSMS should be a Battery Fire and Explosion Prevention and Mitigation Plan, especially in the light of the choice of LFP for the battery chemistry. No explosion hazard analysis has been provided by CHSP.
  3. There is no evidence in the BSMS that full account has been taken of the forensic engineering failure analyses available, including Arizona (2019), Liverpool (2020), Moorabool (2021) and Beijing (2021). This is expected in the NFCC Guidance and its neglect has led to design failures and inadequacies.
  4. The likelihood of a single cell failure somewhere in the BESS increases in proportion to the total size (in MWh) of the system. For very large systems such as Cleve Hill, a single cell failure somewhere may become a routine event which may propagate into a thermal runaway accident. It is estimated that 6% of all BESS worldwide have been subject to some battery failure. This is now an established fact and it is a matter of great concern that contrary to the views of world scientific experts, CHSPL base their approach on their statement ‘’The likelihood of a major accident or disaster is considered to be extremely unlikely’’(112) and go on to base their modelling on the statement ‘’..the most credible worst-case thermal runaway has been considered to be a single enclosure (out of 112) simultaneously entering into thermal runaway.’’(113). They go on to extend this to two enclosures in their section (115-) on airborne pollution from a thermal runaway event. (my underlining)
  5. Container-to-container propagation of BESS accidents has occurred in reality. In the case of the Big Battery fire in Australia in 2021 (Moorabool, near Geelong), one Tesla megapack went into thermal runaway and despite firefighting measures to cool the surrounding area and despite thermal barriers, the adjacent megapack also went into thermal runaway. In Beijing there was propagation to a second cabin, spatially separated, thus apparently not from a thermal mechanism. An electrical surge cause may be conjectured, and presents a further accident escalation mode requiring consideration. “Remote propagation” to a non-adjacent cabin in Beijing was what killed two firemen in a surprise explosion.
  6. The maximum possible scale of a BESS accident increases in proportion to the total size of the system. The claim that BESS accidents will likely be confined to one or at most two enclosures is not credible when fires escalating to neighbouring containers have actually occurred, or have been averted only by strenuous efforts by FRSs. Moreover escalation to spatially separated containers as noted above was reported in the Beijing incident.
  7. The site layout based on 6m spacing between power blocks (22), (confusingly referred to as containers elsewhere), is the minimum recommended by the NFCC Guidance and fails to take account of extensive previous experience of fire propagation. Eye-witness reports from fire service professionals in two separate incidents in Arizona (2012 fire and the 2019 “deflagration”) both reported flame lengths up to 75 feet [22 9 metres] laterally. If 23 metre flame lengths are recorded, then in the absence any other measures, this suggests a minimum safety separation of 23 metres, in all directions, to pre-empt the possibility of power-block to power-block escalation. Even this would not prevent distant escalation by an electrical fault mode, as conjectured from the Beijing incident.
  8. The section (115-) and the Hoare Lea report, Appendix C, are totally inadequate to judge the dangers and risk to life of airborne pollutants from a possible BESS fire. The Davion Hill analysis on the Arizona event reports:

‘’Toxic gases are also present in a Li-ion battery thermal runaway event. HCl, HF, and HCN are all emitted from common plastics fires (from the battery containers). HCl evolves from Polyvinyl Chloride at temperatures above 100 °C. By 200 °C HCl evolution is strongly evident, becoming rapid at 230 °C and dehydrochlorination is very rapid at 300 °C. Carbon dioxide (CO2), carbon monoxide (CO), and water form from the dehydrochlorinated residue at high temperatures. In fact, a common signature of a suspected battery thermal runaway event is the presence of HCN, HCl, or HF as well as HCl and HCN.’’ 

The Hoare Lea analysis, clearly completed at the last minute (16/8/23), lacks credibility in that its main focus (12 pp) is on the irrelevant possibility of a thermal runaway event which does not involve a fire and excludes HCN, HCl and specifically HF (para 2.1.1), the most toxic of likely airborne pollutants. In a short two page Appendix to the report after a preamble asserting  that a fire is the ‘‘unlikely event ignition occurs during a thermal runaway event’’  they report a modelling analysis only of HF from a two-container fire. They conclude that AEGL level 1 (notable discomfort, irritation or certain asymptomatic non-sensory effects) will be exceeded at a distance of 282 m. The nearest habitation is 300m to the south of the batteries.

The details are inadequate to judge the veracity of the Hoare Lea work but the fact that it is wholly inconsistent with reliable literature data on aggregate emissions per unit Wh of energy storage capacity, including published peer-reviewed data, leads us to advise that SBC cannot rely upon such an analysis.

Alternatively with regard to toxic emissions the Atkins report for HSE(NI) provides well-established plume dispersal modelling for an example but relevant and rational “reference case” (single container 5 MWh BESS), and provides contours based on the HF concentrations reached at various distances, for concentrations assessed by reputable agencies in the UK and elsewhere corresponding to the following levels:

IDLH = Imminent Danger to Life and Health

AEGL-3 (30 min) = Acute Exposure Guideline Levels (30 minute exposure)

AEGL-3 (10 min) = Acute Exposure Guideline Levels (10 minute exposure)

 SLOT = Specified Level of Toxicity ( used by HSE in relation to Planning advice )

SLOD = Significant Likelihood of Death

 Again this represents rational risk analysis against concentrations known (e.g.) to risk death in highly susceptible people (SLOT) or 50% mortality (SLOD). In the Atkins illustration, the much more serious  IDLH level of HF is reached 240m downwind of the source, alarmingly sufficiently close to the nearest commercial and residential properties at Crown Cottages (300m) to be of concern.

As noted in detail in our previous submission water volumes allowed for in the proposal (27) are wholly insufficient to control a fire even in a small 1 MWh BESS. Since this point is critical we reproduce below our earlier submission on this point:

  • 9. Large lithium-ion battery fires require very significant quantities of water and can reignite many times after the initial incident. Many of the BESS fires to date have taken days to bring under control and have used and required vast volumes of water to both cool the containers (rather than try to put the fires out directly) and, where necessary, to contain toxic fumes via fogging. The developers appear to misunderstand this and are relying on the NFCC generic suggestion of a water cooling system capable of delivering 'no less than 1,900 litres per minute for at least two hours' This would deliver a total of only 228,000 litres. They therefore propose (27) a firewater tank of this size. There is limited data on the measurement of water volumes deployed in previous BESS fires. However, there are at least two well-documented incidents which indicate that the requirement is much larger and will be needed over many more hours, if not days: The 2017 fire and explosion at Moorabol, Victoria, Australia took 900,000 litres over 6 hours for a 4.25MWh fire  while Drogenbos, Belgium took 1.4million litres for a 1MWh fire These are very small BESS compared to the now proposed 300 MWh Cleve Hill BESS and the larger the BESS, the greater the risk of widespread propagation and the greater the risk of multiple simultaneous fires. Escalation was narrowly forestalled in Liverpool only by the continuous presence of Merseyside FRS for 56 hours cooling the neighbouring container with uninterrupted hydrant water from urban fire hydrants. At the standard 1,900 litres per minute this implies a water volume of over 6 million litres.

Summarising the above experience in terms of the proposed CHSP water tank, Drogenbos (1 MWh) took 4 such tanks, Moorabol (4.25MWh) took 6, suggesting a  significant under sizing of the Cleve Hill storage tank even if a fire is confined to a single container. The Appendix A detailed design drawing is neither detailed nor clear as to how the stored energy is arranged, but from a slightly more detailed diagram in the Hoare Lea report we can surmise that there are 48 containers implying each to be 6.25 MWh. Scaling up the Moorabol data to a 6.25 MWh fire implies close to a need for nine CHSP water tanks while the Drogenbos data suggests a 37-fold undersizing.  This is a serious matter which requires a significant re-design of the site layout.

It should be noted that the Hoare Lea analysis in the BSMP allows for a fire of four hours duration – a further example of inconsistency in the plan.

  • 10. The proposed aerosol type automatic fire suppression system (32) is not specified and could therefore be dangerous. The McMicken, Arizona BESS had a “clean-agent” (inert gas or aerosol) fire suppression system (which deployed correctly). The detailed independent analysis by DNV concluded that the fire suppression system (designed to “smother” a fire) actually contributed to the explosion by creating a stratified atmosphere in which flammable gases could build up unhindered by actual burning, until mixed with air caused by first responders opening a door, when immediate ignition resulted causing life-changing injuries to firefighters.
  • 11. There is no evidence that CHSPL has applied for hazardous Substances Consent (HSC). The current Sunnica NSIP Examination has received  detailed evidence that HSC is almost certainly a legal requirement. The ExA has delayed the publication of his decisions for two months while considering this matter.

Under the “loss of control” provisions of Schedule 1 Part 3 P(HS)Regulations 2015, substances  integral to the battery cells of a BESS are Hazardous Substances (HS). Published calculations have established that LFP BESS of  22MWh and above generate Controlled Quantities (CQ) of HS  as defined in the P(HS)Regulations 2015. The HS are HF and other acute toxic gases. We believe that HSC should be sought by CHSPL.

  • 12. Finally we wish to stress the importance of detailed technical input from the HSE and EA, not just the local FRS. It is not simply a “fire safety” matter. KFRS  cannot be expected to shoulder the responsibility for assessing the effectiveness of suppression systems for controlling thermal runaway (which is not a “fire” in the conventional sense), nor for issues such as the toxin levels and eco-toxicity of unplanned discharges of contaminated fire water into an ecologically sensitive site. The hazards presented by Li-ion BESS are shared by other large scale industrial plant involving dangerous or hazardous substances for which the existing regulatory regime comprises the P(HS)Regs 2015 (at the Planning stage) and the COMAH Regulations 2015 (at the operational stage).  It should be noted that these are wholly agnostic as to technology and explicitly cover “loss of control of the processes”. Policy in National Planning Statement (NPS) EN-1 clearly envisions, where dangerous substances above prescribed thresholds may be present, or foreseeably generated, the early involvement of the COMAH Competent Authority, comprising the HSE and the EA “acting jointly”. The involvement of HSE, or of the EA, alone does not constitute “acting jointly. The systematic safety appraisal from the COMAH Competent Authority required by Sect 4.11.4 of NPS EN-1 is the appropriate level of safety appraisal, but there is no evidence that this has  happened.
  • 13. It is an unreasonable burden to place responsibility for these major issues entirely on the local FRS or to regard their generally sound advice within the bounds of their responsibilities as complete reassurance. Further advice and assessment are essential to provide the complete reassurance required.
  • 14. In the light of the almost weekly occurrence of further events in battery storage facilities and the expectation of responses from consultees to the points we raise, the Faversham Society reserves the right to make further submissions beyond the 28/9/23 deadline.


In addition to the matters above the following requirements listed in the BSMP Appendix B as Additional Information Requested by KFRS in their pre-consultation response. Almost all of this information is missing from the BSMP

1. The battery chemistries being proposed (Provided)

2. The battery form factor (e.g. cylindrical, pouch, prismatic)

3.-6. Provided

7. A detailed diagram / plan of the site.

8. Evidence that site geography has been taken into account (e.g. prevailing wind conditions).

9. Access to, and within, the site for FRS assets

10. Details of any fire-resisting design features

11. Details of any: a) Fire suppression system b) On site water supplies (e.g. hydrants, EWS etc) c) Smoke or fire detection systems (including how these are communicated) d) Gas and/or specific electrolyte vapour detection systems e) Temperature management systems f) Ventilation systems g) Exhaust systems h) Deflagration venting systems.

12. Identification of any surrounding communities, sites, and infrastructure that may be impacted as a result of an incident.

Adherence to National Fire Chiefs Council (NFCC) Guidance The Grid Scale Battery Storage System Planning

 - Guidance for FRS requires: Site Access

- At least 2 separate access points to the site to account for opposite wind conditions / direction. - Roads / hard standing capable of accommodating fire service vehicles in all weather conditions. As such there should be no extremes of grade.

- A perimeter road or roads with passing places suitable for fire service vehicles.

- Road networks on site must enable unobstructed access to all areas of the facility. - Turning circles, passing places etc size to be advised by FRS depending on fleet. Access between BESS units and unit spacing - The presence of High Voltage DC Electrical Systems is a risk and their location should be identified.

- Exclusion zones should be identified.

+++ end +++

September 27, 2023

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